1. Field of the Invention
This invention relates to a single lens reflex camera with an automatic exposure control circuit, and more particularly to a single lens reflex camera with an automatic exposure control circuit including a light measuring photodetector and an exposure information indicating means provided in a viewfinder optical system of the camera.
2. Description of the Prior Art
It has been known in the art in a camera with an automatic exposure camera to measure the light coming through the taking lens and indicate the results of the measurement in terms of exposure information such as a shutter speed within the field of view of a viewfinder optical system by means of a light emitting indicator composed of light emitting diode elements.
In this type of cameras, a photodetector is provided in a viewfinder optical system to receive light coming through the taking lens by way of a swing-up mirror and a focusing plate.
This type of cameras suffer from the defect that the response of the automatic exposure control circuit is slowed when pictures are successively taken or the scene brightness is low. While the shutter is released, the swing-up mirror is moved up and the light coming through the taking lens of the camera is prevented from impinging upon the photodetector in the viewfinder optical system. Therefore, when the light again impinges upon the photodetector after the shutter operation for the previous exposure is finished, it takes some time for the automatic exposure control circuit including the photodetector to recover its normal level of measurement and output the true value of the scene brightness. Particularly when the pictures are successively taken as in a motor driven camera, the automatic exposure control is not able to follow the fast repeated exposures, and accordingly, correct exposure is not always obtained. Further, when the scene brightness is low, the response of the exposure control circuit including the photodetector is low.